Magnetic sensors are used in many applications, e.g. for speed sensing. Speed sensors include sensors which sense a rotation of an element around an axis and are capable to output signals indicative of a rotational speed of the sensor. Magnetic speed sensors use a magnetic field variation caused by a rotation of the element to sense the rotational speed. Magnetic speed sensors can be used in many applications for example to sense a rotation speed of a wheel, a cam shaft, crank shaft or a transmission. Typically, magnetic encoders such as pole wheels or ferromagnetic gear wheels are mounted on the rotating axis to generate magnetic field variations based on the rotation of the axis. For some applications, bias magnets may be provided close to the sensor to provide a biasing magnetic field.